COMPLIANCE INFO_1992-1993 - Laserfiche WebLink

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Mr. Kevin T. Haroff Nage 9 0 According to NIOSH, no absolutely safe concentrations can be ,established for a carcinogen. NIOSH, therefore, recommends that the exposure limits for carcinogens be the lowest concentration that can be reliably detected by the recommended method of environmental monitoring (NIOSH Interim Report NO. 1.• HETA 88-119) . 2n 1984, in a public hearing on occupational exposure to asbestos, NIOSH stated that there is no safe concentration of exposure to asbestos. At that time, given the infeasibility of reducing all exposure to zero and the imprecision of air measuring techniques, NIOSH recommended an exposure threshold of 100,000 particles per cubic meter. Hence, "acceptable" exposure levels for asbestos are not based on what is "safe" but rather on what is measurable and attainable. Although the Department has no information to lead it to believe that free crystalline silica is as potent in terms of fibrogenicity as asbestos, both are known carcinogens. Though not comparable in terms of potency, it is reasonable, as has been done in the March 9, 1990, ENSR report, to draw a parallel between silica (especially free crystalline silica) and asbestos, another fibrous material whose hazard is with respect to inhalation. If the 80 percent upper confidence limit of the total concentration of free crystalline silica (regardless of particle size) within the waste were below a concentration of one percent, much the same as with the Department's Total Threshold Limit Concentration of one percent for asbestos (regardless of particle size) in Section 66699 (b) , 22 CCR, the ash could be considered nonhazardous. In the data provided to the Department, the mean concentration of free crystalline silica in the ash is 16 percent, with an 80 percent upper confidence limit of 18.8 percent. CONCLUSIONS/RECOMMENDATIONS The ash generated by the Wadham facility is a low carbon ash containing a high percentage of free crystalline silica. The data provided indicates that a portion of this free silica is respirable, and that more of the remainder, under normal handling conditions, could become respirable. Inhalation of free crystalline silica may cause or contribute to the development of silicosis or cancer. Section 25117, HSC, defines hazardous waste as: ". . .a waste or combination of wastes, which because of its quantity, concentration, or physical, chemical, or infectious characteristics may either: (a) Cause, or significantly contribute to an increase in mortality or an increase in serious irreversible, or incapacitating reversible, illness.